Neuroendocrine Tumors of the Thymus: Outcomes after Surgical Resection and Prognostic Factors

  Objective  To discuss the clinical manifestations, surgery-based therapy of neuroendocrine tumors of the thymus (NETT) and the potential prognostic factors.

  Methods  We selected 26 consecutive cases diagnosed, treated, and confirmed as NETT by postoperative pathology between December 2004 and December 2013 in Peking Union Medical College Hospital, including 18 males and 8 females. Their clinical manifestations, imaging findings, surgery-based therapy, perioperative complications, and follow-up were retrospectively analyzed.

  Results  The median age of the 26 cases was 46(13-75)years and the median duration of disease was 3.5(1-84)months. Early detection of NETT was difficult due to occult onset and nonspecific clinical manifestations. Seven cases were complicated with Cushing's syndrome and 1 case with multiple endocrine neoplasia type 1. Thoracic contrast-enhanced computed tomography showed mass in the region of thymus. All the cases received thoracotomy and 22 cases got macroscopically radical resection, with 3 cases developing complications and no perioperative death. Sixteen cases received adjuvant therapy after the surgery. Pathologically, there were 20 well differentiated cases (8 typical carcinoids and 12 atypical carcinoids), and 6 poorly differentiated cases (5 small cell and 1 large cell neuroendocrine tumors). There were 4 Masaoka-Koga stage Ⅰ cases, 3 stage Ⅱ cases, 12 stage Ⅲ cases, and 7 stage Ⅳ cases. After long-term follow-up, the median survival was 51.0 months, and 3- and 5-year survival rates were 71.0% and 44.6%, respectively. Multivariate analysis showed that degree of tumor differentiation (P=0.039) and staging (P=0.012) had impact on prognosis.

  Conclusions  NETT is a rare malignancy with tremendous aggressiveness. Early confirmed diagnosis and therapy is still a big challenge due to nonspecific clinical manifestations. Thoracic contrast-enhanced CT could help detect the tumor and evaluate the possibility of surgery. Stage and differentiation of the tumor might be major prognostic factors.